A man who grew from East Texas roots into one of America's wealthiest men died this weekend.

Dallas billionaire and philanthropist Harold Simmons died Saturday night. He was 82 years old.

His wife Annette told The Dallas Morning Newsthat her husband died at Baylor University Medical Center at Dallas. She said he'd been in Baylor's intensive care unit for the last eight days, the newspaper reported. She did not give the cause of death.

Simmons, who made his fortune through investing and corporate takeovers, had an estimated net worth of $10 billion.

In 2008, Simmons bankrolled ads linking Obama, then a U.S. senator and presidential candidate, to William Ayers, a controversial Vietnam-era activist who helped found the violent Weather Underground. Simmons was also a key backer of the "Swift Boat Veterans for Truth" attacks on Democratic presidential candidate John Kerry in 2004.

Simmons, has given tens of millions of dollars to Republican candidates, including Texas Gov. Rick Perry and former presidential candidate Mitt Romney.

Perry issued the following statement Sunday afternoon:

“Harold Simmons was a true Texas giant, rising from humble beginnings and seizing the limitless opportunity for success we so deeply cherish in our great state. His legacy of hard work and giving, particularly to his beloved University of Texas, will live on for generations. Anita and I send our thoughts and prayers to the Simmons family.”

“Dallas has lost a truly generous giant,” said Doug Curtis. “The Simmons’ generosity has touched so many parts of our city. The Center considers itself fortunate to have the Simmons’ name gracing such a prominent part of our beautiful opera house. Our thoughts and prayers go out to the Simmons family.”

East Texas Roots

Simmons, born to two school teachers in East Texas, became one of the richest men in the country with interests ranging from energy to chemicals. He currently sits at No. 40 on Forbes' list of the 400 wealthiest Americans.

According to a biography on his namesake foundation's website, Simmons earned his bachelor's and master's degrees from the University of Texas.

He decided at the age of 29 to buy a small Dallas drugstore, according to his biography. He went on to buy Williams Drug Co. in 1966 and 30 more drug stores the next year, followed by an $18 million buyout of Ward's Drugstores in 1969. He sold his stores in 1973 for $50 million in Eckerd stock. He then started a career as an investor, buying major positions in publicly traded companies.

Simmons' has given tens of millions to Texas organizations, including charities, medical groups, education groups and civic organizations. A UT Southwestern Medical Center said his donations to their institution alone approached $200 million.

Attorney General Greg Abbott noted in a statement that Simmons "shared his success with the state he dearly loved, giving generously to make advancements in healthcare and to improve higher education."

"Harold Simmons was one of my best friends, and it's never easy to say goodbye to close friends," Texas oil tycoon T. Boone Pickens said in a statement. "Harold accomplished so much in his life. He was a passionate person -- passionate about his family, his business, philanthropy and politics. ... We should all leave such a rich legacy behind."